The innermost of the veils of nothingness, the last emanation before being itself and a bunch of other absurd qabalistic bullshit.

Man, "ain-soph-aur." That shit comes right after "ain-soph," and right before "kether" in the successive abstractions of the existential and near-mathematical progression from nothingness to abstract being to manifestation envisioned by some crazy jewish dudes a couple thousand years ago.